Wndsn Quadrant Telemeter: The Quadrant Side

The Quadrant side hosts an angular quadrant, an inclinometer, a shadow square, and trigonometric arcs.

Initial Quadrant Setup

Wrapping the string around from the Telemeter side.

Thread the string through the slot at the top corner of the quadrant. Ensure free and perpendicular hanging of the weighted string through the vertex.

Quadrant and Inclinometer Operation

Slope, quadrant, and inclinometer scales.

Quadrant and inclinometer operation: Note that while the quadrant measures the degrees (or percent) from horizontal, the inclinometer measures the degrees from vertical.

With the α scale on the front side of the Telemeter, we can measure angles between two arbitrary points, both of which have to be visible at the same time to align the scale.

With the quadrant, as well as the inclinometer on the reverse, we measure angles relative to the perpendicular which the plumb line provides. This means that, e.g. if we know the height of a landmark, but we only see the upper part of it, with the base obscured by other structures, and we know that we are on the same level as that landmark, we can determine its angular height by simply sighting its highest point.

For the quadrant

Align near and far part of the sighting edge with the object to be measured.

Steady the string and let it hang freely and perpendicular.

On the quadrant scale, read the angular size (or altitude) of the object.

Alternatively, on the slope scale, you can read the percentage of slope.

For the inclinometer

Align the left-hand side of the quadrant with the tangible object to be measured.

Steady the string and let it hang freely and perpendicular.

On the inclinometer scale, read the degrees from vertical.

Transversal inclinometer scale

Versions of the Quadrant Telemeter have a special transversal scale for the 30 degree inclinometer.

The 30 degree scale at the bottom of the quadrant side is graduated in 1 degree increments. The graduations are further refined by a set of transversals which allow finer readings of 0.25, 0.5, and 0.75 degrees where the transversals cross the horizontal grid lines. We are using a modified transversal in our instrument, reduced to the part of the line that is relevant to our reading without clogging up the full degree marks.

Using our string, the closest point where the transversal crosses the grid is determined. The horizontal grid lines are divided in quarters by the transversals, diagonally between full degrees thus indicating the fraction of the graduation for the measure.

The graduations of the transversal inclinometer scale. The reading is 26° 45".